Rapid, high-frequency, and theta-coupled gamma oscillations in the inferior occipital gyrus during face processing

Sato, W.*, Kochiyama, T.*, Uono, S., Matsuda, K., Usui, K., Inoue, Y., & Toichi, M. (* equal contributors)

脳画像研究は，顔に対して他の刺激よりも，下後頭回（IOG）が強く活動することを報告してきた．しかし，顔処理におけるIOG活動の時間・周波数・機能特性は不明であった． 我々はこの問題を，顔・モザイク・家を正立・倒立で呈示しIOGの頭蓋内脳波を計測することで調べた． 時間周波数解析から，正立顔に対して正立モザイクおよび正立家よりも強いガンマ波活動が，110～ms・40～300Hzで示された．位相振幅異周波数結合解析から，正立顔に対して正立モザイクおよび正立家よりも顕著なシータ波とガンマ波の結合が，115～256msで示された．正立顔と倒立顔では，約100～200msのガンマ波は同等であったが，約200～msでは活動の違いとシータ波との結合パタンの違いが示された．こうしたパタンは，右IOGで左IOGよりも顕著であった． こうした結果および他の脳領域間コミュニケーションの知見から，他領域から伝達されるシータ波を受けて，右IOGの広周波数帯のガンマ波が，すばやく多段階（部分処理も全体処理も）の顔処理を遂行することが示唆される．

Cortex http://dx.doi.org/10.1016/j.cortex.2014.02.024

Neuroimaging studies have found greater activation in the inferior occipital gyrus (IOG), or occipital face area, in response to faces relative to non-facial stimuli. However, the temporal, frequency, and functional profiles of IOG activity during face processing remain unclear. Here, this issue was investigated by recording intracranial field potentials in the IOG during the presentation of faces, mosaics, and houses in upright and inverted orientations. Time–frequency statistical parametric mapping analyses revealed greater gamma-band activation in the IOG beginning at 110 msec and covering 40–300 Hz in response to upright faces relative to upright houses and mosaics. Phase–amplitude cross-frequency coupling analyses revealed more evident theta–gamma couplings at 115–256 msec during the processing of upright faces as compared with that of upright houses and mosaics. Comparable gamma-band activity was observed during the processing of inverted and upright faces at about 100–200 msec, but weaker activity and different coupling with theta-band activity after 200 msec. These patterns of activity were more evident in the right than in the left IOG. These results, together with other evidence on neural communication, suggest that broadband gamma oscillations in the right IOG conduct rapid and multistage (i.e., both featural and configural) face processing in collaboration with theta oscillations transmitted from other brain regions.

Copyright(C) 2014 PRI ().